1. Field of the Invention
The present invention relates to fibers and films having excellent heat resistance, mechanical properties and luster prepared by conventional wet or dry processes. More particularly, the fibers and films are prepared from a composition consisting of an aqueous emulsion which consists either of a polymer or copolymer obtained by polymerizing vinyl chloride and/or vinylidene chloride or vinyl chloride and/or vinylidene chloride and another monomer in the presence of polyvinyl alcohol derivatives containing a sulfone or sulfate group and a catalyst, in the substantial absence of an emulsifier, and a matrix consisting essentially of polyvinyl alcohol.
In the following descriptions, polyvinyl chloride, polyvinylidene chloride and polyvinyl alcohol are abbreviated as PVC, PVdC and PVA, respectively. Except for the description in the Examples, the expression "polyvinyl chloride" may represent "polyvinyl chloride and/or polyvinylidene chloride or a copolymer with vinyl chloride and/or vinylidene chloride".
2. Description of the Prior Art
For preparing emulsion spun fibers of PVC and PVA as the major constituents, U.S. Pat. No. 3,111,370, incorporated herein by reference, describes a process in which a PVC emulsion, prepared by emulsion polymerization in an aqueous PVA solution using a polymerization catalyst and a large amount of emulsifying agent, is mixed with an aqueous solution of PVA as the matrix and the resulting mixture is used for spinning fibers.
The fibers and films prepared by the above process are adequately hydroscopic and excellent in softness and antiinflammability because they contain both hydrophobic PVC and hydrophilic PVA as the major constituents. But, on the other hand, those properties, such as, heat resistant, mechanical and luster are inevitably lowered due to the large amount of emulsifying agent which is used in the emulsion polymerization and remains as a contaminant in the resulting fibers and films.
In the process of emulsion polymerization, an anionic emulsifying agent is generally used which is rather unstable when heated. The thermal decomposition products therefrom accelerate thermal decomposition of the PVC which is poorly heat resistant. This leads to discoloration of the produced fibers and films.
On the other hand, the low molecular weight emulsifying agent that is contained as one of the constituents in the processed fibers and films can deleteriously affect the mechanical properties, transparency, and luster of the products. Thus, the presence of such a low molecular substance may promote the nonuniformity in the fine structure of the product.